1.p=m*v,where p is the momentum,m is the mass,and v is the velocity.The momentum is a vector.
2.Newton's Third Law:
For every action,there is an equal and opposite reaction.
3.To the left.
4.Mass is a measurement of the amount of matter something contains,while weight is the measurement of the pull of gravity on an object.
One difference:the mass of an object doesn't change when an object's location changes.The weight,however,can change with location.